LED module with a stabilized leadframe

Abstract

A LED module for use in a LED light, preferably a LED retrofit lamp, has a leadframe and one or more LEDs which are electrically and mechanically connected to the leadframe. The LED module has one or more stabilizing sections made from an insulating material which are introduced locally, preferably in a punctiform and/or linear manner, into intermediate spaces of the leadframe in order to fasten sections of the leadframe to one another and, preferably, to space them apart from one another.

Claims

1. A light-emitting diode (LED module for use in a LED light, the LED module comprising: a leadframe having a plurality of sections, wherein the plurality of sections define intermediate spaces in the leadframe; a plurality of LEDs that are electrically and mechanically connected to the leadframe; and a plurality of stabilizing sections which are physically separate and individually distinguishable from one another and made from an insulating material, wherein the plurality of stabilizing sections is introduced locally into the intermediate spaces of the leadframe, and wherein the plurality of stabilizing sections fastens the plurality of sections of the leadframe to one another.

2. The LED module according to claim 1, wherein the plurality of stabilizing sections is introduced locally in a punctiform manner.

3. The LED module according to claim 1, wherein the insulating material is at least one material selected from the group consisting of a polymer, a glass, a ceramic, and a surface-mounted device (SMD) component with insulating properties.

4. The LED module according to claim 1, wherein at least one surface of the leadframe substantially has no contact with the insulating material of the plurality of stabilizing sections.

5. The LED module according to claim 4, wherein the at least one surface of the leadframe is substantially uncovered.

6. The LED module according to claim 1, wherein the intermediate spaces of the leadframe are electrically insulating and are not filled, in that the intermediate spaces completely penetrate the leadframe in a direction of a thickness of the leadframe.

7. The LED module according to claim 1, wherein the leadframe is at least partially bent.

8. The LED module according to claim 7, wherein two of the sections of the plurality of sections of the leadframe are bent towards one another, wherein the two of the sections are spaced apart and connected by the plurality of the stabilizing sections.

9. The LED module according to claim 1, wherein the leadframe is equipped with LEDs on a first side of the leadframe and on an opposing second side of the leadframe.

10. The LED module according to claim 1, wherein the LEDs are arranged in at least one manner selected from the group consisting of lattice-like, linear, and circular.

11. The LED module according to claim 1, wherein the LEDs are: connected by the leadframe in series; or connected by the leadframe in a combination of series and parallel connections.

12. A method for producing the LED module according to claim 1, the method comprising: producing the leadframe from a sheet using a process selected from the group consisting of stamping, cutting, and etching; equipping the leadframe with the LEDs by connecting the LEDs electrically and mechanically to the leadframe; and stabilizing the leadframe by local introduction of the insulating material into the intermediate spaces of the leadframe so that the stabilizing sections are formed.

13. The method according to claim 12, wherein producing the leadframe involves keeping connection bars and transport sections attached to the leadframe, wherein the connection bars and transport sections are not part of a finished form of the LED module.

14. The method according to claim 12, wherein the insulating material is at least one material selected from the group consisting of a polymer, a glass, a ceramic, a cement, and an insulating surface-mounted device (SMD) component with insulating properties.

15. The method according to claim 12, wherein the leadframe is not encapsulated, partially or completely, by a substrate material.

16. The method according to claim 12, further comprising roughening at least one surface of the leadframe.

17. The method according to claim 12, further comprising coating at least one surface of the leadframe with a material selected from the group consisting of tin (Sn), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), zinc (Zn), and nickel (Ni).

18. The method according to claim 12, further comprising finishing at least one surface of the leadframe with at least one finish selected from the group consisting of a light-reflecting coating, an engraving, a laser engraving, and a photochemical etched structure.

19. The method according to claim 12, further comprising bending the leadframe.

20. The LED module according to claim 1, wherein the plurality of stabilizing sections is introduced locally in a linear manner.

21. The LED module according to claim 1, wherein the plurality of stabilizing sections does not overlap to form a structure on an order of magnitude of the leadframe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a and 1b show a LED module from the front (FIG. 1a) and from the rear (FIG. 1b) with a stabilized leadframe which is equipped with a plurality of LEDs.

(2) FIGS. 2a and 2b show a LED module according to a further exemplary embodiment, wherein the LED module is shown before (FIG. 2a) and after (FIG. 2b) a bending operation of the leadframe.

(3) FIG. 3 shows a LED module according to a further exemplary embodiment.

(4) FIG. 4 shows a LED module according to a further exemplary embodiment.

(5) FIGS. 5a to 5c show a LED module according to a further exemplary embodiment, wherein the partial FIGS. 5b and 5c show different bending and fitting configurations.

(6) FIGS. 6a to 6c show a LED module according to a further exemplary embodiment which has a two-part leadframe; in this case FIGS. 6a and 6b show a semi-finished product during manufacture and FIG. 6c shows the complete LED module.

(7) FIGS. 7a to 7c show possible applications of LED modules according to different exemplary embodiments in a LED light.

(8) FIGS. 8a, 8b and 8c show semi-finished products for the manufacture of LED modules.

(9) FIGS. 9a to 9h show leadframe geometries of different exemplary embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

(10) The drawing descriptions are described below with reference to the drawings. In this case elements which are the same, similar, or act in the same way are provided with identical reference numerals in the different drawings, and repeated description of some of these elements is omitted in order to avoid redundancies.

(11) FIG. 1a shows a LED module 1 according to a first exemplary embodiment, considered from one side which may be designated here as the front side. FIG. 1b shows the LED module 1 from the opposite side, i.e. the rear side.

(12) The LED module 1 has a leadframe 10, which is a metallic lead frame stamped out or cut out of a sheet. The leadframe 10 can be manufactured for example from a cost-effective material, such as for instance steel, or a material with high thermal conductivity, such as for instance copper. In particular materials which can be used for printed circuit boards (PCBs) are suitable. If a magnetic material is used, for instance magnetic steel, the connection of the LED module 1 and the optical adjustment can be simplified. Moreover, the leadframe 10 can be coated for example with a Sn or Ni layer. Connectors 11 are soldered onto the leadframe 10 or are integral components of the leadframe, for fastening and for electric connection in a light (cf. FIGS. 7a to 7c).

(13) The leadframe 10 forms conductive tracks which in the present example of FIGS. 1a and 1b enable a series connection of a plurality of LEDs 12. For this purpose, the LEDs 12 are mounted by means of a SMD process on corresponding connection points on the leadframe 10. Since the LEDs 12 in each case bridge an insulating intermediate space 13 of the leadframe 10, the LEDs 12 contribute to a stabilization of the leadframe 10.

(14) For further and definitive stabilization of the leadframe 10 punctiform or linear stabilizing sections 14 are provided, which are made from an insulating materialfor example polymer, glass, cement, ceramic or insulating SMD componentsand bridge one or more intermediate spaces 13 which in this case are gaps. The stabilizing sections 14 are introduced at least in part into intermediate spaces 13, in order to stabilize the corresponding sections of the leadframe 10 and to space them apart from one another. The stabilizing sections 14 are characterized in that they are provided locally at points on the leadframe 10 at which a spacing and stabilization is necessary in order to ensure the mechanical and electrical functionality of the LED module 1. Thus the stabilizing sections 14 are provided in particular in spaces 13 so as to prevent an inadvertent bending together and contacting of sections of the leadframe 10 which are to be insulated electrically.

(15) The LED module 1 thus constructed functions without a stabilizing housing and without a plastic substrate in which the leadframe 10 is completely or substantially embedded. In particular it is not necessary to provide an injection molding machine and a method step of encapsulation of the leadframe 10 with a substrate material. Moreover, since the LED module 1 uses the leadframe 10 without a substrate, it is particularly flexible, three-dimensionally malleable and thus can be used flexibly for different LED lights. The production process is simplified by comparison with a LED module with a plastic substrate, and the production costs as well as the product costs are reduced. Moreover, due to the high thermal conductivity of the leadframe 10 and the open construction of the LED module 1 a buildup of heat is effectively prevented, so that in some variants special measures for heat dissipation can be omitted.

(16) The leadframe 10 can be equipped with LEDs 12 on one side or on both sides.

(17) According to an exemplary embodiment which is shown in FIGS. 2a and 2b, light emission can also be achieved on both sides in that the stamped-out or cut-out, equipped and stabilized leadframe 10 (FIG. 2a) is bent, as shown in FIG. 2b. In such cases one or more of the stabilizing sections 14 can be used synergistically as spacers between the leadframe sections which are bent towards one another. Alternatively or in addition, spacers made from an insulating material, for instance a plastic, can be attached to the leadframe 10.

(18) Moreover, if insulating magnets are used as spacers, the bent leadframe sections can be fixed to one another in a simple and original manner.

(19) Since the leadframe 10 is bent in a manufacturing step, the light emission characteristic can be adapted in a simple manner. In particular a light emission on both sides can be achieved according to the exemplary embodiment of FIG. 2b, without the need to equip the leadframe on both sides. This simplifies the production process. Moreover, in this way the cooling effect can be improved, since the heat produced by the LEDs can be dissipated from a larger leadframe surface.

(20) FIG. 3 shows a LED module 1 according to a further exemplary embodiment, in which the leadframe 10 has a planar circular form. A three-dimensional form of a leadframe 10, which is achieved by bending of sections of the leadframe sheet, is disclosed in the exemplary embodiment according to the FIG. 4.

(21) FIG. 5a shows a LED module 1 according to a further exemplary embodiment which has a leadframe 10 with stamped-out or cut-out lead frame sections 10. The leadframe sections 10 can be bent individually, so that a flexible light emission characteristic can be achieved. In particular the basic shape of FIG. 5a can be bent in a different manner and equipped with LEDs 12, as shown in FIGS. 5b and 5c, so that a flexibly adjustable light distribution can be achieved in a simple manner.

(22) FIGS. 6a to 6c show a group of further exemplary embodiments, which are directed to a LED module 1 having one single LED 12, for instance for use in single-spot lights. The leadframe 10 is divided into two, with a gap 13 between the two leadframe sections 10a and 10b. In this case FIG. 6a shows a semi-finished product 200, in which the two leadframe sections 10a and 10b are connected to one another by stabilizing sections 14. At the same time the stabilizing sections 14 reliably space the two leadframe sections 10a and 10b apart from one another. Furthermore, in FIG. 6a two contact sections 15 are shown which are configured for connection to a SMD component, for example a simple connector or a spring contact. In this case FIG. 6b shows a semi-finished product 200, in which the two leadframe sections 10a and 10b can also be connected to one another by a connection bar 201 (see FIG. 8a or FIG. 8b). FIG. 6c shows the LED module 1 after the leadframe 10 of the semi-finished product 200 is equipped with a LED 12.

(23) FIGS. 7a to 7c show exemplary applications of the LED modules 1 described above for a LED light 100, which has the external form of a conventional light bulb with an Edison base. Generally speaking, the LED light 100 can be a so-called LED retrofit lamp which is designed for use in conventional sockets. For this purpose, the LED light 100 preferably has a LED driver (not illustrated) which converts the mains voltage provided by the socket into an appropriate form for the LEDs 12.

(24) It may be pointed out that the LED module 1 can be used in various ways, for example in tubular lamps which are designed for fluorescent tube bases, LED reflector lamps, LED strips, LED light filaments, surface light panels, spotlights, floodlights, linear lights, high-bays, torches, wall and/or ceiling lights etc. In particular in the case of LED lights with large LED printed circuit boards the described leadframe design can be used advantageously.

(25) For the production of the LED module 1, according to an exemplary embodiment first of all a plurality of leadframes 10 are stamped out or cut out of a conductive sheet, as shown in FIG. 8a, optionally retaining connection bars 201 and/or transport sections 202, which temporarily mechanically stabilize the semi-finished product 200 for transport and further processing and remove them at a later time. Moreover, the leadframes 10 can be prepared from pre-assembled perforated and/or slotted sheets, in order to save cutting time during the individual cutting out. Furthermore, the surface of the leadframe 10 can be roughened and/or coated. If as a result the heat emission factor of the leadframe 10 is increased, this leads to a temperature drop on the LEDs 12. Moreover, the light yield can be increased by a coating. In a further manufacturing step, the one stabilizing section or the plurality of stabilizing sections 14 are introduced or attached, since an insulating material (for example polymer and/or glass and/or ceramic) is introduced at least partially into intermediate spaces 13 of the leadframe 10, for example injected. In a manufacturing step which can be carried out previously, simultaneously or subsequently, the LEDs 12 are fastened on the leadframe 10, so that a semi-finished product 200 is produced from a plurality of leadframes 10 which are equipped and connected to one another, which is shown schematically in FIG. 8b. Equipping the leadframe 10 with the LEDs 12 can take place by means of a SMD process. Thus the leadframes 10 can be provided at the corresponding points with a soldering paste, then equipped with the LEDs 12 and heated, so that the soldering paste melts and joins the leadframe 10 and the connectors of the LEDs 12. The connection and the fastening of the LEDs 12 can also take place in a technically different manner. Moreover, solder points can be created for mechanical stabilization and/or electrical connection of leadframe sections. Furthermore, in a further manufacturing step, connectors 11 are soldered to the leadframe 10 if they are not already formed integrally or in one piece as components of the leadframe 10. The above-mentioned connection bars 201 and/or transport sections 202, if present, are removed. In a further manufacturing step, if applicable, the LED modules 1 can be brought into the required three-dimensional shape by bending.

(26) In order to ensure a high mechanical stability of the leadframe semi-finished product during the SMD assembly process, the transport sections 202 or parts thereof can be provided with a U-, V-, W- and/or L-shaped structure. This is shown by way of example by FIG. 8c. In this case the transverse direction of the sheet unwound from the roll is preferably bent. If in this case the transport sections 202 are only profiled or bent downwards, any doctor blade process (application of SMD soldering paste) is not hampered. This stabilization measure significantly increases the rigidity of the sheets in the production process and contributes to the possibility of using thinner sheets, for example <0.6 mm thick. The transport sections 202 are preferably planar at least on the long edges, for example with a width of approximately 10 mm, in order to simplify the transport process. During separation of the leadframe semi-finished products out of the sheet roll, a U-, V-, W- and/or L-shaped profiling of the transport sections 202 is preferably already made for stabilization.

(27) In the exemplary embodiments set out above, the LEDs 12 are connected in series by the leadframe 10. However, different geometries, i.e. circuits and three-dimensional arrangements of the LEDs 12, can be implemented. By way of example reference may be made to the leadframe geometries of FIGS. 9a to 9h.

(28) FIG. 9a shows a flat lattice arrangement of series-connected LEDs 12 on a leadframe 10. The stabilizing sections 14 reliably ensure the mechanical stability and electrical functionality of the LED module 1. FIG. 9b shows a geometry in which the LEDs 12 are likewise series-connected and arranged like a lattice, but functions with few stabilization points 14. As a result, the LED module 1 of FIG. 9b can be bent particularly flexibly, so that it is suitable for special light forms, such as for instance omnidirectionally emitting lights. According to this exemplary embodiment the electrical contact between sections of the leadframe 10 is implemented partially by contact sections 16 which for example can be produced by soldering. After the bending the three-dimensional form of the leadframe 10 can be fixed for example by further stabilizing sections 14. A partial parallel connection of LEDs 12 is disclosed in the exemplary embodiment of FIG. 9c, in order to show that the described concept of the reinforced leadframe 10 is not limited to series-connected LEDs 12. FIGS. 9d to 9f show exemplary embodiments of a strip-shaped stabilized leadframe 10 with stabilizing sections 14 attached in various ways. In this case the LEDs 12 are series-connected. A strip-shaped stabilized leadframe 10 with parallel connected LEDs 12 is disclosed by FIG. 9g. A mixture of parallel connected and series connected LEDs 12 is disclosed by FIG. 9h.

(29) If applicable, all individual features which are set out in the exemplary embodiments can be combined with one another and/or exchanged for one another, without departing from the scope of the invention.

LIST OF REFERENCES

(30) 1 LED module 10 leadframe 10 leadframe section 10a leadframe section 10b leadframe section 11 connection 12 LED 13 intermediate space/gap 14 stabilizing section 15 contacting section 16 contact section 100 LED light 200 semi-finished product 201 connecting piece 202 transport section